# [TRNSYS-users] Equation and Type 20

Baboo Gowreesunker Baboo.Gowreesunker at brunel.ac.uk
Mon Jun 17 11:06:23 PDT 2013

```Tobias for no.1.

A primitive way of doing this is in Equation-Editor:

let x = PV-power

first = GT(x,1.5)*LT(x,3)
second = GT(x,3)*LT(x,4.5)
third = GT(x,4.5)

heating_rate = (1.5*first)+(3*second)+(4.5*third)
You should be able to pass the 'heating_rate' to other types

I don't know about no. 2.

Regards
Lesh

________________________________
From: Tobias Tag [tag.tobias at googlemail.com]
Sent: 17 June 2013 09:53
To: TRNSYS-users at cae.wisc.edu
Subject: [TRNSYS-users] Equation and Type 20

Dear TRNSYS-User,

i have two problems with TRNSYS 17.

1. I´m trying to make the maximum heating rate of an element (of Type 60c)  depending on the power produced by PV in three steps. Shold look like that:

If 1.5kW < PV-Power < 3kW  then heating rate = 1.5 kW

else if 3kW < PV-Power < 4.5kW then heating rate = 3kW

else if PV-Power > 4.5kW then heating rate = 4.5kW

I´ve set the heating rate as a String variable which shold get the value from a equation. but i don´t know how to update the equation in every time step of the simulation.

2. Does anybody know what the external files of type 20 (dual source heat pump) are? Unfortunatly ther is no example in the TRNSYS-Examples folder.

Kind regards

Tobias
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